These are designed to be used with the Blichmann BoilerMaker Brew Kettles for use in a mash tun. Will also work great if you're using whole hops in your boil kettle (for pellet hops, we recommend using the Blichmann HopBlocker). A patent pending button louver design is a hybrid of a perforated false bottom and a slotted manifold to give you the best of BOTH designs!